Microseismic Monitoring: Engineering Value and Validation

Microseismic Monitoring:Engineering Value and Validation

Norm WarpinskiPinnacle – A Halliburton Service

2© 2011 HALLIBURTON. ALL RIGHTS RESERVED.

Microseismic Monitoring – An Engineering Tool Microseismic monitoring is a

valuable tool for optimizing– Well layout (trajectory)– Well spacing– Stage lengths– Perf clusters and/or valves & packers– Stimulation design– Fracture height and length– Complexity– SRV– Diverter behavior– Fault interactions & geohazards– Calibrated fracture model Environmental issues

– Fracture height growth (aquifers)– Seismicity

SPE 145463, Mayerhofer et al.

Marcellus shale


Downhole microseismic monitoring Array of receivers

– Positioned in nearby well

– Approximately at the depth of the treatment

3-component geophone systems ¼ to ½ msec sampling

State-of-the-art microseismic receiver arrays

Fiber-optic wirelines

Wall-lock clamped tools

Array apertures of 500 – 1,500 ft

Vertical Up V

H2 H1

Clamp ArmIn Back

Tri-Axial Sensors (Geophones)

Calibrated Velocity Model


Fracture Behavior: Wide Variations Sandstones

– Relatively planar– Piceance basin

Mesaverde example Barnett Shale

– Intrinsic complexity• Low stress bias• Weak natural fractures

– Enhanced by slick water stimulations

Other shales and most carbonates?– Full spectrum of

behavior

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0

200

400

600

800

1000

-600 -500 -400 -300 -200 -100 0 100 200

Sout

h-N

orth

(m)

West-East (m)

Barnett

Mesaverde

SRV

Planar


Microseismicity Distribution

Microseisms are distributed approximately proportionately:– Near tips (length and height)– Around fracture face

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-20

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0 20 40 60 80 100 120 140

Dept

h fro

m ce

nter

of p

erfs

, m

Time, min

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Dist

ance

alon

g fra

ctur

e len

gth,

m

Time, min

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800

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-1400 -1200 -1000 -800 -600 -400 -200 0 200

North

ing,

m

Easting, m

SPE 148780 Canadian sedimentary basin example

Interior eventsTip events

Interior eventsTip events


Fracture StabilityPlan View

Shear zones

max

min

Compressive zone

All stresses compressiveIncreased frictional forcesDecreased shearSTABILIZED

Tensile zone

All stresses tensile:Reduced frictional forcesIncreased shearDESTABILIZED

x

y

x

y

Leakoff effects into natural fractures


Hydraulic Fracturing and Microseismicity Microseisms

– Fracture tip• Tensile events?• Shear events ahead of

fracture– Leakoff into natural

fractures• Shear events

– Increased pressure– Slippage on natural

fractures• Tensile events

– Fissure opening– Network

• Combination of both of above


Where Would These Microseisms Likely Occur? Intersections of natural

fractures, faults, and bedding planes provide suitable sites for shear processes

Coal

DOE mineback testsSPE 15258

&SPE 16422


Fracture Behavior in Multi-Stage, Multi Cluster Completions


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Nor

thin

g, m

Easting, m

Stage 1Stage 2Stage 3Stage 4Stage 1Stage 2Stage 3Stage 4

Monitor well

Treatment well #1

Treatment well #2

Microseismic Interpretation Understanding biases and

artifacts– Distance limitations– Radial appearance– Noise hindrance– Fracture effects

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North

ing,

m

Easting, m

Monitor well

Stage 3:Minimal noise

Stage 6:Fracture intersects

monitor well

Stage 8:Excessive noise


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SOUT

H-NO

RTH

(m)

WEST-EAST (m)

M-Site Length & Azimuth Validation Intersecting Well

Drilled Prior To Fracturing Microseismic

Events Recorded During Fracturing & Compared At Time When Pressure Began To Increase In The Intersecting Well

Primary validation experiments:M-Site – microseismic, tiltmeters, intersection wells, tracers, pressure interferenceMounds Drill Cuttings – microseismic, tiltmeters, intersection wells, tracersMitchell Barnett – microseismic, surface & downhole tiltmeters, offset wells

MWX-3

MWX-2

Intersection well

Point of intersection


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4300

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4600

4700-10 -5 0 5 10

DE

PTH

(ft)

TILT (microradians)

FE -- 67 ft5B data6B data

0 20 40 60

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4300

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4700

Frequency

4400

4500

4600

4700-300 -100 100 300 500

DEP

TH (f

t)

ALONG FRACTURE LENGTH (ft)

B SAND

Fracture Height Versus Downhole Tiltmeter Data M-Site

– Monitoring with 6 tiltmeters cemented in place across from treatment interval

– Fracture height deduced from inversion of tilt data using 3D Finite Element model

– Very good agreement between bulk of microseismic data and tilt results

– Several microseismic outliers

Linear gel minifracs– 2 identical injections– 400 bbl– 22 bpm

Inverted tilt fracture height

Microseismic depth histogram


Microseismic Mapping Results

Well 2H (completed first)Well 1H (completed next)

N45°E to N55°E, Xf= 600 to 1,000 ft (most events <500 ft)

hf=250 – 480 ft; wnf=370 -920 ftPressure interference for all fractures

Well 1H Fracture Stimulation

Time (min)

Surf Press [Csg] (psi) Bottomhole Press (psi)Slurry Flow Rate (bpm) Slurry Density (lbm/gal)

60293 60812 61330 61849 62367 62885 0

1700

3400

5100

6800

8500

3900

4100

4300

4500

4700

4900

0

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0.0

2.0

4.0

6.0

8.0

10.0

53 71 174 181 318 46 ?Pressure rise


Production Interference

Core Area Barnett Shale

Shut-ins cause corresponding rate increase in other well


Shallow Microseismicity: What is it?

Bakken example Dohmen et al.SPE 166274

Side view of zones of microseismicityin two wells in the Bakken

Large amount of activity 800 to 1,000 ft above the Bakken


Downhole Tiltmeter Assessment of Height Growth

Hybrid tools with both microseismic and tiltmetermonitoring provide additional information– Where actual deformation is

occurring– Likelihood of hydraulic

connectivity

Cases:– Heights: 50, 100, 200 ft– Net pressure: 1000 psi– Modulus: 5e+6 psi– Length > monitoring distance

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0100200300400500

-200 -100 0 100 200

Dept

h fro

m ce

nter

of fr

actu

re, f

t

Tilt, microradians

H=50 ftH=100 ftH=200 ft

-500-400-300-200-100

0100200300400500

-75 -25 25 75

Dept

h fro

m ce

nter

of f

ract

ur, f

t

Tilt, microradians

Two FracturesH=100 ft


Integrating Microseismic and Fiber Optics Microseismicity

– Uncertainty of fracture initiation, entrance conditions & number of fractures

Fiber optics provides near-wellbore information– Diversion– Control DTS DAS


Source Mechanisms Analysis of waveforms to determine

“fault” characteristics Requires:

– 2 wells– High quality data

• Low noise• Good coupling

– Accurate locations– Accurate velocity models Provides:

– “Fault-plane” orientations– Slippage direction– Strength of the microseism– Volumetric behavior Major issue:

– Uncertainty• Everything looks volumetric

n

u

Some claim it can show fractures closing!Impossible to create a closure microseism in a fluid filled fracture (try clapping underwater)

It should tell us something about the reservoir


Hydraulic Fracture Energy Budget Total energy of fracturing operation

– ~ 50 gJ Strain energy of hydraulic fractures

– Single fracture ~ 6 gJ (12%)– Three fractures ~ 18 gJ (36%) Microseismic energy

– Typically ~ 10 – 100 kJ– One part in 106 to 109

Quasi-static process

Typical Marcellus treatmentH = 250 ftL = 700 ftP = 800 psiwavg = 0.015 inmin = 6,000 psiQ = 90 bpm for 90 min

A DFN built on microseismic data alone is missing >99.9999% of the deformation


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140001 1001 2001 3001 4001 5001 6001

Dept

h, ft

Fracture stages

Mapped Microseismic Height: North American Shales Top: shallowest microseism; Bottom: deepest microseism

SPE 145949

Typical aquifer depths

Fracture tops

Fracture bottoms

Average perforation depth

BarnettMarcellusEagle FordHaynesvilleWoodfordMuskwa


Summary of Observed Seismicity – Shales Microseismic

monitoring provides detailed data on potential for seismic events– Number of monitored

fractures approaching 50,000

0

50

100

150

200

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300

350

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1

Freq

uenc

y

Moment Magnitude

MuskwaWoodfordHaynesvilleEagle FordMarcellusBarnett

0

50

100

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300

350

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

Freq

uenc

y

Moment Magnitude

MuskwaWoodfordHaynesvilleEagle FordMarcellusBarnett

Largest microseism observed

Typical size of seismic event that can just be felt

Similar to Richter magnitude


Summary

Microseismicity provides valuable information about fracture behavior and completion effectivenessMicroseismic monitoring does have issues that need to

be considered when interpreting results The interpretation of microseismicity benefits when

integrated with other diagnostics. Care needs to be taken when attempting to use source

mechanism information


NASA photo:

Shiprock

Shiprock dike, Louis Maher photograph

Questions?

Documents

Microseismic Monitoring: Engineering Value and Validation